Sheeting materials having a graphic image or other mark have been widely used, particularly as labels for authenticating an article or document. For example, sheetings such as those described in U.S. Pat. Nos. 3,154,872; 3,801,183; 4,082,426; and 4,099,838 have been used as validation stickers for vehicle license plates, and as security films for driver's licenses, government documents, tape cassettes, playing cards, beverage containers, and the like. Other uses include graphics applications for identification purposes such as on police, fire or other emergency vehicles, in advertising and promotional displays and as distinctive labels to provide brand enhancement.
One type of imaged sheeting is disclosed in U.S. Pat. No. 6,288,842 and U.S. Pat. No. 7,068,434. These two patents disclose microlens sheeting with composite images, in which the composite image floats above or below the sheeting, or both. The composite image may be two-dimensional or three-dimensional. A laser impinging on a microlens array is focused at the backside of the array where a radiation sensitive coating is applied. Other microlens sheetings are formed when material is transferred onto the back of a microlens array, such as described in U.S. Published Patent Application 2007/0081254.
Each of these previously disclosed methods rely on the application of radiation from a laser or other radiation source to form each sheeting having a composite image.
U.S. Pat. No. 5,712,731, “Security Device for Security Documents Such as Bank Notes and Credit Cards,” (Drinkwater et al.) discloses a security device that includes an array of microimages which, when viewed through a corresponding array of substantially spherical microlenses, generates a magnified image. In some cases, the array of microlenses is bonded to the array of microimages.
PCT Patent Application Publication, WO 03/061983 A1, “Micro-Optics For Article Identification” discloses methods and compositions for identification and counterfeit deterrence using non-holographic micro-optics and microstructures having a surface relief greater than a few micrometers.